Understanding
Cats and Predation
From
Alley Cat Allies
website © 2000. Reprinted with permission.
While many
studies have shown that cats do not have a detrimental impact on
wildlife on continents, there are several who feel that cats are
to blame for the depletion of songbirds and other animals. Two studies
most often quoted are the Stanley Temple study and the Churcher
/Lawton study. Some groups use these studies in misguided effort
s to discredit our work to humanely control feral cats. Over sixty
studies have been done on different continents all showing three
very important points:
Cats
are opportunistic feeders, eating what is most easily available.
Feral cats are scavengers, and many rely on garbage and hand-outs
from people.
Cats
are rodent specialists. Birds make up a only small percentage of
their diet when they rely solely on hunting for food.
Cats
may prey on a population without destroying it. If this weren't
so, we would no longer have any mice around.
Even though
some cats can become efficient hunters and do kill birds, many international
biologists agree that only on small islands do cats possibly pose
a severe threat to the wildlife populations. They agree with biologist
C.J. Mead that "Any bird populations on the continents that
could not withstand these levels of predation from cats and other
predators would have disappeared long ago..."
And finally,
while many concentrate their efforts on blaming cats, the real culprit
homo sapiens, goes free; continuing the destruction of habitat,
hunting and killing, and using pesticides that endanger entire populations
of wildlife, including millions of birds. The following is a collection
of opinions from experts who have studied predation and who do not
lay the blame on cats.
OPINIONS
FROM EXPERTS
Excerpted
from Understanding Cats by Roger Tabor, 1995
"From
the mid-nineteenth century mankind's own numbers and destruction
of huge areas of virgin planet surface have exploded exponentially.
As man thrived, so did the domestic cat due to the massive increase
in food supply for both house and feral animals." page 8-9
"Cats
hunt, catch prey, and eat it - they are carnivores. To expect them
not to hunt is unreasonable both because of their biology and the
natural order of things. Almost incredibly, in the USA there is
a growing idea that carnivores are somehow immoral. Although that
view may be extreme, that cats catch birds causes cat-owning bird
lovers much concern..."
"While
the size of the range of rural feral cats reflects their prey requirements,
prey is not necessary for the survival of domestic house cats, their
range sizes are independent of its abundance. While this could make
them more of a danger to wildlife, this does not occur for a number
of reasonsÉ. Not all house cats are competent hunters, and most
only catch prey occasionallyÉ.. Although cats are superb hunters,
it is their scavenging ability that allows them to survive as feral-living
animals and live with us eating food off a saucer..."
"Contrary
to common belief, cats do not catch many birds, but mainly small
mammals. Proportionately, town cats will catch more birds than their
country cousins. What is often overlooked is that although cats
are far more common in towns than in the country, so are birds!
As well as feeding cats, we also feed birds. We provide artificial
nest sites in the form of nestboxes and buildings. Our gardens provide
good habitat in the form of rich scrubland, with excellent insect
support due to an increased flowering time in the year, and lawns
with abundant earthworms. Our actions can be seen as providing optimum
conditions to maximize bird numbers! Consequently, when Chris Mead
of the British Trust for Ornithology assessed the numbers of ringed
garden birds caught by cats, he found that they were not having
a harmful effect on bird populations..." pages 101-102
Are concerns
of cat predation and effects on birds/wildlife valid?
Jeff Elliott
wrote an extensive article for The Sonoma County Independent, "The
Accused," March 3-16, 1994, where he investigated findings
frequently used to implicate cats in the decrease of wildlife populations.
Here is an excerpt from the article listing the studies and his
findings of their accuracy.
"But what
do those studies actually say? And how good is the science in them?
Here's some background on the two most frequently mentioned studies,
cited in Cats and Wildlife: A Factsheet from the National Audubon
Society. "Britain's 5 million cats kill about 20 million birds
per year."
"Studying
the hunting trophies brought home by 78 cats in a single English
village, Peter Churcher and John Lawton found birds were 35 percent
of the kill-by far the highest estimate in any such study. In a
1989 condensation for Natural History magazine, they multiplied
their results by the estimated number of cats in the entire nation.
Rarely are projections made with such limited data, except in junior
high science projects - which may be an appropriate comparison,
considering Churcher teaches at a boys' school.
'Researchers
in Wisconsin cite cats for killing 19 million songbirds.'
"Doctor
Stanley Temple, co-author of this frequently quoted work, seemed
exasperated when asked again to rehash his findings. 'The media
has had a field day with this since we started," he sighed.
Those figures were from our proposal. They aren't actual data; that
was just our projection to show how bad it might be.' No one interviewed
has seen Temple's unpublished research.
"But the
[Sonoma County] supervisors appeared to give special attention to
a letter written by Drs. Peter Connors and Victor Chow, UC/Davis
researchers working at the Bodega Marine Laboratory. By projecting
the numbers cited from Wisconsin and Great Britain, they estimated
500,000 Sonoma County birds are killed by cats annually. In a telephone
interview, Connors said he has read only the condensation of the
British study and has seen only "extracted forms" of Temple's
work-which, of course, were guesstimates for the proposal. He was
surprised to learn this study was unpublished. 'Look, we're not
cat researchers,' said Connors. 'I've never worked with cats at
all; I'm an ornithologist.' Then what expertise does he have about
cats? 'Vic (Chow) has been participating in a mentor program with
Piner High School students on a project tracking feral cats,' he
explained. 'We had (radio transmitter) collars on three animals.
We didn't do a full study; it's just a program with high school
students.'"
Claws and
Purrs; Understanding the Two Sides of Your Cat (1992, Sidgwick and
Jackson, London); p. 164 Peter Neville, Director of the Center of
Applied Pet Ethology in the United Kingdom
"In England,
at least, there is no evidence to suggest that the occasional high
mortality of birds due to pet cats has had any damaging effect on
even one species of bird, however distressing to birds, bird lovers
and cat owners that predation may beÉ"
"In any
case, as we have seen, the strategy used by cats for catching birds
is not hugely successful at the best of times and only increases
in efficiency when the birds stalked are more vulnerable or less
able to escape."
B.M. Fitzgerald,
Ecology Division, Department of Scientific and Industrial Research,
New Zealand Mead has studied various aspects of feral cats (home
range, effect on birdlife, food) and the effects of various predators
on local wildlife, since 1970, in New Zealand.
"As Mead
(1982) emphasized, the birds in suburban and rural parts of Britain
have co-existed with cats for hundreds of generations. And they
may now be under less pressure from cats than they were in the past
from a variety of assorted natural predators. Any bird populations
on the continents that could not withstand these levels of predation
from cats and other predators would have disappeared long ago."
Gary J.
Patronek, VMD, Ph.D. Tufts University, Letter to Editor, Journal
of the American Veterinary Medical Association, Vol. 209, No. 10,
November 15, 1996
"If the
real objection to managed colonies is that it is unethical to put
cats in a situation where they could potentially kill any wild creature,
then the ethical issue should be debated on its own merits without
burdening the discussion with highly speculative numerical estimates
for either wildlife mortality or cat predation. Whittling down guesses
or extrapolations from limited observations by a factor of 10 or
even 100 does not make these estimates any more credible, and the
fact that they are the best available data is not sufficient to
justify their use when the consequences may be extermination for
cats.
"If asking
for reasonable data to support the general assertion that wildlife
mortality across the United States attributable to cat predation
is unacceptably high can be construed as Ôattempting to minimize
the impact,' then I am guilty as charged. What I find inconsistent
in an otherwise scientific debate about biodiversity is how indictment
of cats has been pursued almost in spite of the evidence."
Excerpted
from a speech by John Terborgh, Director of the Center for Tropical
Conservation at Duke University at the Manomet Symposium in 1989,
Smithsonian Institution, Washington, DC;
"The global
environmental crisis has caught up with migratory birds. There are
simply too many people making ever increasing demands on a fixed
supply of resources. It is inconceivable that we can continue on
the same reckless path for very long."
"The conversion
of forests to cropland, pasture and urban sprawl, the downgrading
of virgin stands to second growth, and the conversion of mixed forests
to pine monoculturesÉ The inescapable implication of this for conservation
is that there is only a limited amount of time left in which to
slow human population growth and to institute other fundamental
changes in the countries of this hemisphere or many of our migratory
birds will be little more than memories."
"One country
after another will pass the 100 per square kilometer population
threshold in the coming two or three decades. After this has happened,
there is really not much that can be done to salvage winter habitat
for migratory birds."
What Then
is Responsible for the Decreasing Number of Birds?
Biologist
Dr. Robert Berg
"Habitat
destruction: As man's development of the planet continues, available
habitat for animals and plants is being carved up into smaller pieces.
The fragmentation of ecosystems separates populations genetically
from each other, and if a particular habitat is not large enough,
remnant populations contained within them are doomed due to genetic
inbreeding. If there are not enough large areas, chance occurrences
such as an extremely harsh winter, floods, localized disease, etc.,
can drive remaining populations to the brink of extinction.
"Some
species are dependent on environmental policy in more than one place.
One endangered species of bird, Bachman's warbler, is disappearing
not because there is a scarcity of riverine swampland in the (Southeast)
United States in which it breeds, but because it used to winter
in the forests of western Cuba virtually all of which have been
cleared for sugar cane.
"In some
cases other birds have been responsible for the demise of some bird
species. Kirtland's warbler, already compressed into a small remaining
jack-pine country in Michigan, was subjected to nest parasitism
by the brown headed cowbird laying its eggs in their nests. The
baby cowbirds push the Kirtland's own young from the nest and are
then raised by these hapless birds. The European starling has spread
across the United States since its introduction in the early 1900's,
depriving many of our resident and less aggressive birds of habitat.
In the words of Pogo, 'We have met the enemy and he is us'."
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